<!-- 组件：轮播 -->
<template>
  <div class="slide-show" @mouseover="clearInv" @mouseout="runInv">
    <div class="slide-img">
      <a :href="slides[nowIndex].href">
        <transition name="slide-trans">
          <img v-if="isShow" :src="slides[nowIndex].src" alt="">
        </transition>
        <transition name="slide-trans-old">
          <img v-if="!isShow" :src="slides[nowIndex].src" alt="">
        </transition>
      </a>
    </div>
    <h2>{{ slides[nowIndex].title }}</h2>
    <ul class="slide-pages">
      <li @click="goto(prevIndex)">&lt;</li>
      <li v-for="(item, index) in slides" @click="goto(index)">
        <!-- 用于判断当前哪个是激活的状态 -->
        <a :class="{on: index === nowIndex}">{{index+1}}</a>
      </li>
      <li @click="goto(nextIndex)">&gt;</li>
    </ul>
  </div>
</template>

<script>
export default {
  // 接收组件的属性（参数）
  props: {
    slides: {
      // 接收数组
      type: Array,
      default: []
    },
    // 定义轮播的时间
    inv: {
      type: Number,
      default: 1000
    }
  },
  // 变量
  data () {
    return {
      nowIndex: 0,  //banner设置默认第一张图片
      isShow: true  //控制图片动画
    }
  },
  //计算属性
  computed : {
    // 前一张
    prevIndex () {
      if (this.nowIndex === 0){
        return this.slides.length - 1
      }else {
        return this.nowIndex - 1
      }
    },
    // 后一张
    nextIndex (){
      if (this.nowIndex === (this.slides.length - 1)){
        return 0
      }else {
        return this.nowIndex + 1
      }
    }
  },
  // 方法
  methods: {
    // 轮播进入下一张
    goto (index) {
      this.isShow = false
      setTimeout(() => {
        this.isShow = true
        this.nowIndex = index
        this.$emit('onchange', index)// 子组件向父组件进行通讯（调用onchange方法）
      },10)
    },
    // 间隔一秒轮播下一张图片
    runInv (){
      this.runId = setInterval(() => {
        this.goto(this.nextIndex);
      },this.inv)
    },
    // 鼠标移入，停止轮播
    clearInv (){
      clearInterval(this.runId);
    }
  },
  //渲染完毕后执行
  mounted () {
//    console.log(this.slides) 轮播的图片
    this.runInv()

  }
}
</script>

<style scoped>
  .slide-trans-enter-active {
    transition: all .5s;
  }
  .slide-trans-enter {
    transform: translateX(900px);
  }
  .slide-trans-old-leave-active {
    transition: all .5s;
    transform: translateX(-900px);
  }
  .slide-show {
    position: relative;
    margin: 15px 15px 15px 0;
    width: 900px;
    height: 500px;
    overflow: hidden;
  }
  .slide-show h2 {
    position: absolute;
    width: 100%;
    color: #fff;
    background: #000;
    opacity: .5;
    bottom: 0;
    height: 30px;
    text-align: left;
    padding-left: 15px;
  }
  .slide-img {
    width: 100%;
  }
  .slide-img img {
    width: 100%;
    position: absolute;
    top: 0;
  }
  .slide-pages {
    position: absolute;
    bottom: 10px;
    right: 15px;
  }
  .slide-pages li {
    display: inline-block;
    padding: 0 10px;
    cursor: pointer;
    color: #fff;
  }
  .slide-pages li .on {
    text-decoration: underline;
  }
</style>
